1. Field of the Invention
The present invention relates to an image processing method, a computer-readable storage medium, and an information processing apparatus.
2. Description of the Related Art
In recent years, as information tends to be digitalized, image processing apparatuses such as printers or facsimiles used to output digitalized information or scanners used to digitalize documents have been essentials. The image processing apparatus usually has an imaging function, an image forming function, a communication function, and the like, and thus are configured as a multifunction machine which is usable as a printer, a facsimile, a scanner, and a copying machine.
Among such image processing apparatuses, a printer (hereinafter, referred to as an “ink jet printer”) employing an ink jet scheme is known as an example of a printer used to output digitalized information. The ink jet printer includes a recording head with a nozzle ejecting ink, and performs image forming by applying pressure to an ink liquid chamber in the recording head through a PZT (PbZrO3—PbTiO3) element, a heater element, or the like and ejecting ink onto a sheet of paper which is a recording medium.
The ink jet printer performs image forming by ejecting ink in units of pixels forming an image of image data converted to a certain resolution based on the image data. Further, the ink jet printers are classified into a printer in which the density to express each pixel is a one gradation, that is, only chromatic and achromatic colors are distinguished and a printer in which three gradation expressions of dark, normal, and light are available according to its specification in addition to achromatic color.
On the other hand, in image data used for image forming/outputting, each of pixels configuring an image is configured to have more gradations than expressiveness of the density by the ink jet printer. For this reason, when image forming/outputting is performed by the ink jet printer, a half-toning process is performed by converting original image expressed by multiple gradations into gradations according to the expressiveness of the ink jet printer and preventing an image quality from deteriorating when viewed by people.
As examples of the half-toning process, a dithering technique and an error diffusion technique are known, and in recent years, a technique of directly obtaining and processing an error such as a direct binary search (DES) technique has been used as well (for example, see Japanese Laid-open Patent Publication No. 2009-171014).
In the ink jet printer, there is a problem in that a desired image is not formed due to a variation in characteristics (hereinafter, referred to as “landing characteristics”) of ink which is ejected from the nozzle and fixed onto a sheet of paper. Examples of the landing characteristics include the size, the position, and the shape of ink ejected from the nozzle.
In recent years, for example, ink jet printers of a line type in which a plurality of heads is lined up and arranged in a longitudinal direction have been used. According to this type, it is possible to form an image of a wide range at a time, and thus it is possible to increase productivity by the ink jet printer.
However, in order to form an image of a wide range at a time, it is necessary to mount many nozzles, and the problem related to the landing characteristics of the nozzle is consequential as well. Particularly, since image forming/outputting are performed by single scanning, nozzles forming images of respective scanning lines are arranged at narrow intervals, and a variation in the landing characteristics between the nozzles has strong influence on the image quality.
Thus, in order to perform desired image forming/outputting using performance of an image forming/outputting engine, it is necessary to perform control according to characteristics of the image forming/outputting engine such as the landing characteristics of the nozzle.
Therefore, there is a need for image forming/outputting according to characteristics of the image forming/outputting engine without deteriorating the image quality.